YOUNG AND FRESNEL: A CASE-STUDY INVESTIGATING THE PROGRESS OF THE WAVE THEORY IN THE BEGINNING OF THE NINETEENTH CENTURY IN THE LIGHT OF ITS IMPLICATIONS TO THE HISTORY AND METHODOLOGY OF SCIENCE A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF SOCIAL SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY BY YEVGENIYA KULANDINA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS IN THE DEPARTMENT OF PHILOSOPHY SEPTEMBER 2013 Approval of the Graduate School of Social Sciences Prof. Dr. Meliha Altunışık Director I certify that this thesis satisfies all the requirements as a thesis for the degree of Master of Arts. Prof. Dr. Ahmet İnam Head of Department This is to certify that we have read this thesis and that in our opinion it is fully adequate, in scope and quality, as a thesis for the degree of Master of Arts. Doç. Dr. Samet Bağçe Supervisor Examining Committee Members Prof. Dr. Ahmet İnam (METU, PHIL) Doç. Dr. Samet Bağçe (METU, PHIL) Doç. Dr. Burak Yedierler (METU, PHYS) I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Last name : Yevgeniya Kulandina Signature : iii ABSTRACT YOUNG AND FRESNEL: A CASE-STUDY INVESTIGATING THE PROGRESS OF THE WAVE THEORY IN THE BEGINNING OF THE NINETEENTH CENTURY IN THE LIGHT OF ITS IMPLICATIONS TO THE HISTORY AND METHODOLOGY OF SCIENCE Kulandina, Yevgeniya MA, Department of Philosophy Supervisor: Doç. Dr. Samet Bağçe September 2013, 78 pages This thesis aims to analyze how Thomas Young and Augustine Fresnel were successful in developing the wave theory of light at the beginning of the nineteenth century. The Methodology of Scientific Research Programmes will be used as the tool of analysis. Such a case-study will give the possibility to access the relative merits of the chosen methodology as well – it will help to point to the benefits of the method and to the parts which are open to further modification. That in turn will allow to discuss general issues appearing in the history and methodology of science, such as the applicability of a certain set of methodological rules to the process of theory-change throughout the flow of scientific development, the status of these rules as a guarantee of objectivity of scientific theories, and the possibility of scientific inquiry as objective process. Keywords: Wave Theory of Light, Young, Fresnel, Methodology of Science. iv ÖZ YOUNG VE FRESNEL: BİLİM TARİHİ VE METODOLOJİSİNE ETKİLER IŞIĞINDA ON DOKUZUNCU YÜZYILIN BAŞINDA DALGA TEORİSİNDEKİ GELİŞMEYİ İNCELEYEN DURUM ÇALIŞMASI Kulandina, Yevgeniya Yüksek Lisans, Felsefe Bölümü Tez Yöneticisi: Doç. Dr. Samet Bağçe Eylül 2013, 78 sayfa Bu tez, Thomas Young ve Augistive Fresnel’in, on dokuzuncu yüzyılın başındaki dalga ışık teorisinin gelişiminde ne kadar başarılı olduklarını incelemektedir. İnceleme aracı olarak, Bilimsel Araştırma Programların Metodolojisi kullanılacaktır. Bu durum çalışması, seçilmiş olan metodolojinin göreceli değerlerinin erişimine de olanak verecektir – çalışma, metodun faydalarına ve düzeltmeye açık noktalarına işaret etmesinde yardımcı olacaktır. Bu da, bir takım metodolojik kuralların teoriler değişimi sürecine bilimsel gelişimin boyunca uygulanabirliği, bu kuralların bilimsel teorilerin objektiflik garantisi olarak statüsü ve bilimsel araştırmanın objektif bir süreç olarak sürdürme olasılığı gibi bilim tarihi ve metodolojisinde çıkan genel meselelerini tartışmak için olanak sağlayacaktır. Anahtar Kelimeler: Dalga Işık Teorisi, Young, Fresnel, Bilim Metodolojisi. v To My Dear Mother vi TABLE OF CONTENTS PLAGIARISM........................................................................................................iii ABSTRACT ....................................................................................................... iv ÖZ ....................................................................................................................... v DEDICATION.................................................................................................... vi TABLE OF CONTENTS ................................................................................... vii LIST OF TABLES ............................................................................................ viii LIST OF FIGURES ........................................................................................... ix CHAPTER I. INTRODUCTION ................................................................................ 1 II. HISTORICAL BACKGROUND: THE HERITAGE ACCOMODATED IN THE WAVE THEORY TILL 1800 .................. 4 III. THOMAS YOUNG AND THE PRINCIPLE OF INTERFERENCE .................................................... 11 IV. AUGUSTINE FRESNEL AND THE CELEBRATED ACADEMY PRIZE ......................................... 21 V. WHY THE METHODOLOGY OF SCIENTIFIC RESEARCH PROGRAMMES? .................................. 43 VI. FURTHER EVALUATIONS ON THE YOUNG-FRESNEL CASE ........................................................ 49 VII. CONCLUSION: WHO MADE THE REVOLUTION IN OPTICS IN THE NINETEENTH CENTURY? ............................ 66 REFERENCES .................................................................................................. 76 APPENDICES A. TEZ FOTOKOPİSİ İZİN FORMU ...................................................... 78 vii LIST OF TABLES TABLES Table 2.1. Young’s observations on diffraction .................................................. 19 Table 3.1. Comparing theory and experiment, the fourth dark band .................... 25 Table 3.2. Table of the numerical values of the integrals .................................... 39 Table 3.3. Comparing theoretical and experimental results on the exterior fringes of red-light of wave-length 0.000638 mm ............................................... 41 Table 3.4. Comparing theory with experiment regarding of positions of maxima and minima in the fringes produced by a narrow aperture ..................... 41 viii LIST OF FIGURES FIGURES Figure 2.1. Constructive and destructive interference ......................................... 16 Figure 3.1. External and internal fringes formed by diffraction from an obstacle ............................................................................... 22 Figure 3.2. Observation of the dark fringe of the fourth order ............................. 25 Figure 3.3. Fresnel’s experiment with mirror and copper cylinders..................... 27 Figure 3.4. Fresnel’s initial explanation of diffraction ........................................ 29 Figure 3.5. Copper plate used in Fresnel’s experiment ....................................... 32 Figure 3.6. The scheme of interference of two waves ......................................... 33 Figure 3.7. Incorporation of the Huygens’s principle to the phenomenon of diffraction of light ............................................................... 36 Figure 3.8. Observation of diffraction from an obstacle ...................................... 37 ix CHAPTER I INTRODUCTION Through the course of its development, scientific activity gives birth to a certain amount of examples, which in turn become quite interesting to investigate from the standpoint of the methodology of science. One of the most suitable candidate for such a methodological analysis would be the process of theory-change. It is found to be convenient since the examination of the shift from one scientific theory to another allows to track and understand the processes taking place during the change by the help of the chosen methodological “tools” of analysis. Moreover, such examination gives a chance to evaluate chosen methodological set of rules as well, test them “in action”, so-to-speak. The shift of “paradigms” from Ptolemy’s geocentric system to Copernicus’s heliocentric picture of the universe, or shift from Newtonian mechanics to the General Theory of Relativity – these can be noticed as the most prominent examples used for such purpose. Still, there are other cases in the history of science which deserve close attention. One of these can be found in optics at the beginning of the nineteenth century, when the particle theory of light, developed by Isaac Newton, was abandoned in the favor of the wave theory of light. This case is fruitful from the methodological point of view not only as a bright example of the process of theory-change; a closer look at it uncovers an interesting fact in that switch. When one reads a book in the history of the wave theory of light (also to be referred as “the wave theory” further), two scientists can be separated as major dedicators to this hypothesis – Thomas Young (1773 – 1829) and Augustine Fresnel (1788 – 1827). The former worked in England; the latter developed his hypothesis in France. There appears to be no concern at the first glance; but a closer examination would show that Young established his theory of light in the early 1800s, but the acceptance of the wave theory among scientists began only twenty years later, after Fresnel announced his hypothesis. If Young had 1 successfully demonstrated his theory as valid, why then it was neglected for almost twenty years? Which factors played role in such a delay? What was there in Fresnel’s formulation about the wave nature of light that allowed to convince the men of science in its validity; and how in that respect Young’s work left incomplete?